Expression of wild rice Porteresia coarctata PcNHX1 antiporter gene (PcNHX1) in tobacco controlled by PcNHX1 promoter (PcNHX1p) confers Na+-specific hypocotyl elongation and stem-specific Na+ accumulation in transgenic tobacco

• Published in: Plant physiology and biochemistry Vol. 139; pp. 161 - 170
• Main Authors: Jegadeeson, Vidya, Kumari, Kumkum, Pulipati, Shalini, Parida, Ajay, Venkataraman, Gayatri
• Format: Journal Article
• Language: English
• Published: France Elsevier Masson SAS 01.06.2019
• Subjects: Chlorophyll - metabolism; Genes, Plant - genetics; Genes, Plant - physiology; Halophyte; Hypocotyl - growth & development; Malondialdehyde - metabolism; Nicotiana; Plant Proteins - genetics; Plant Proteins - metabolism; Plant Proteins - physiology; Plant Stems - metabolism; Plants, Genetically Modified; Poaceae - genetics; Poaceae - physiology; Porteresia coarctata; Promoter Regions, Genetic - genetics; Promoter Regions, Genetic - physiology; qRT-PCR; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae - physiology; Salt stress; Salt-Tolerant Plants - genetics; Salt-Tolerant Plants - metabolism; Seedlings - growth & development; Seedlings - metabolism; Sodium - metabolism; Sodium-Hydrogen Exchangers - genetics; Sodium-Hydrogen Exchangers - metabolism; Sodium-Hydrogen Exchangers - physiology; Vacuolar NHX; Halophyte; ORF; Salt stress; DW; GUS; qRT-PCR; Vacuolar NHX; Porteresia coarctata; NHX; AP
• ISSN: 0981-9428; 1873-2690
• DOI: 10.1016/j.plaphy.2019.03.014

Soil salinization is a major abiotic stress condition that affects about half of global agricultural lands. Salinity leads to osmotic shock, ionic imbalance and/or toxicity and build-up of reactive oxygen species. Na⁺/H⁺ antiporters (NHXs) are integral membrane transporters that catalyze the electro-neutral exchange of K⁺/Na⁺ for H⁺ and are implicated in cell expansion, development, pH/ion homeostasis and salt tolerance. Porteresia coarctata is a salt secreting halophytic wild rice that thrives in the coastal-riverine interface. P. coarctata NHX1 (PcNHXI) expression is induced by salinity in P. coarctata roots and shows high sequence identity to Oryza sativa NHX1. PcNHX1 confers hygromycin and Li+ sensitivity and Na+ tolerance transport in a yeast strain lacking sodium transport systems. Additionally, transgenic PcNHX1 expressing tobacco seedlings (PcNHX1 promoter) show significant growth advantage under increasing concentrations of NaCl and MS salts. Etiolated PcNHX1 seedlings also exhibit significantly elongated hypocotyl lengths in 100 mM NaCl. PcNHX1 expression in transgenic tobacco roots increases under salinity, similar to expression in P. coarctata roots. Under incremental salinity, transgenic lines show reduction in leaf Na+, stem specific accumulation of Na+ and K+ (unaltered Na+/K+ ratios). PcNHX1 transgenic plants also show enhanced chlorophyll content and reduced malondialdehyde (MDA) production in leaves under salinity. The above data suggests that PcNHX1 overexpression (controlled by PcNHX1p) enhances stem specific accumulation of Na+, thereby protecting leaf tissues from salt induced injury. •Yeast strain AB11c expressing PcNHX1 shows Na+ tolerance.•Transgenic tobacco PcNHX1 seedlings show growth advantage in increasing NaCl.•(iv) PcNHX1 tobacco seedlings show growth advantage in increasing MS concentrations.•Etiolated PcNHX1 seedlings show significantly hypocotyl elongation (100 mM NaCl).•Under salinity, transgenic PcNHX1 lines show stem-specific Na+ accumulation.